Death star For the first time astronomers have detected the last gasps of a star being torn apart by a previously dormant giant black hole.

The signals, which came from a galaxy 3.9 billion light years away, were x-rays generated by matter heated to millions of degrees and torn apart as material from the star crosses the black hole's event horizon.

Known as quasi-periodic oscillations, they are a characteristic feature of stellar black holes which have about ten times the mass of the Sun.

"This is telling us that the same physical phenomenon we observe in stellar mass black holes is also happening in black holes a million times the mass of the Sun, and in black holes that were previously asleep," says Reis, who is lead author of the paper published today in the journal Science.